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  <meta charset="UTF-8" />
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  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Document</title>
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<body>
  <script>
    // 严格模式:消除语法中不合理的地方,为 ES 后期发展做铺垫

    // 1.1 整个脚本开启严格模式
    "use strict";

    // num = 10;
  </script>

  <script>
    // 1.2 立即执行函数，作为独立的作用域，开启严格模式
    age = 10;
    (function (a, b) {
      "use strict";
      console.log(a + b);
      // score = 100;
    })(1, 2);
  </script>

  <script>
    // 1.3 函数作为局部作用域开启严格模式

    function sum() {
      "use strict";
      // score = 12;
    }

    function sum1() {
      score = 12;
    }

    sum();
    sum1();
  </script>
</body>

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